The present invention relates to a mechanical device for loosening or breaking beads of pneumatic tires from the rims of the wheels.
It is very difficult to break the beads of pneumatic tires from the rims of wheels, particularly for heavy vehicles such as trucks and trailers, farm tractors and their associated implements, earth movers, aircraft or the like.
In the removal of a tire from a wheel rim, lateral displacement of the tire bead from the indented bead-receiving portion of the rim is required. A section of the bead is laterally displaced by inward movement of that section. After this lateral displacement has taken place, the entire bead may be displaced from the annular depression where it is normally securely seated in operative position on the wheel rim. This lateral displacement of the section of the bead of the tire is known as "breaking the bead".
While the driving of wedge-shaped bead breaking implements between the bead and wheel rim is usually successful to break the bead of a small tire such as tires of automobiles, such a procedure often will not break the bead of a larger tire such as those for farm tractors and heavy equipment. Instead, more sophisticated apparatus, usually in the form of hydraulically-driven wedges or lever arms and the like have conventionally been used to break the beads of such tires and permit their removal from their associated wheel rims. Examples of such devices are illustrated, for example, in Branick U.S. Pat. No. 3,865,172 issued Feb. 11, 1975, Boyle U.S. Pat. No. 3,857,431 issued Dec. 31, 1974 and Branick Canadian Pat. No. 555,821 issued Apr. 15, 1958.
Canadian Pat. No. 856,557 of LePier issued Nov. 24, 1970 describes and illustrates a purely mechanical device for breaking the bead of such a large tire, the device being hand-operated. The device is provided with a clamp so that the device may be firmly clamped onto the wheel rim. Then a displacer element which is threadably connected to a portion of the clamp is rotated and thereby moved towards and into the bead of the tire to displace it and break the bead. For its effective operation, such a device requires it to be firmly gripped to the wheel rim. This requires a preliminary application of a conventional type of starter wedge to be driven by hammer to initially separate a portion of the bead a slight distance from the rim to enable mounting of the device to that rim. As well, because of the force required to clamp the device to the rim to ensure that it does not come loose during the bead breaking operation, distortion of the rim by the clamp may occur.
It is an object of the present invention to provide a hand-operated mechanical device for breaking the beads of pneumatic tires, the device being made up of a minimum of working parts, and which is light in weight and portable and extremely rugged and durable.
It is a further object of the present invention to provide such a device which is capable of generating sufficient power to be used in conjunction with pneumatic tires of large cross-sectional diameters and which may be adjusted so as to be used on tires varying considerably in cross-sectional diameters.